Over the past few decades, free radicals have come to be appreciated increasingly for their importance to human health and disease. Many common and life-threatening diseases, including atherosclerosis, cancer, and aging, have free radical reactions as an underlying mechanism of injury. Over this period of time, our conceptual understanding of the interaction of free radicals with living organisms has evolved and provided unprecedented opportunities for improving the quality and even length of human life.
One of the most common types of free radicals are the reactive oxygen species (ROS). These are the products of normal cell respiration and metabolism and are generally regulated by antioxidants produced in the body. Due to environmental agents such as pollution, and lifestyle factors such as smoking or exercising, the production of free radicals is increased. Such increase may bring the body out of balance, especially as the body ages and the mechanisms that produce antioxidants lose their ability to produce these compounds at their necessary rate, resulting in oxidative stress. The resulting damage can range from disruption of biological processes, killing of cells, and mutation of genetic material, which may lead to the occurrence of cancer.
The potential use of dietary supplements for protection against the effects of oxidative stress and the progression of degenerative diseases and aging has been the subject of an increasing number of studies during the past two decades. In the market today there are many products that contain antioxidants at various levels. These come in the form of foods, liquids and nutritional supplements. The richest sources of these vital nutrients commonly are found in fruits and vegetables having compounds such as Vitamin C, Vitamin E, beta-carotene and others.
The antioxidant hypothesis postulates that supplementation with dietary antioxidants can alleviate the redox imbalance associated with disease. Antioxidants function to bind these free radicals and stabilize and scavenge them out of the system, thereby reducing the amount of damage free radicals may cause.
Synthetic antioxidants such as BHA (butylated hydroxy anisole), BHT (butylated hydroxy toluene) and NDGA (nordihydro-guaiaretic acid) have been developed to date. By way of examples of natural antioxidants, there are antioxidant enzymes such as superoxide dismutase, peroxidase, catalase and glutathione peroxidase, and non-enzymatic antioxidant substances such as tocopherol (vitamin E), ascorbic acid (vitamin C), cartenoid and glutathione.
However, synthetic antioxidants may cause allergic reactions and oncogenesis due to their strong toxicity in the body, and be easily disrupted by heat due to temperature sensitivity. On the other hand, natural antioxidants are safer than synthetic antioxidants in the body but have the problem of weak effect. Therefore, the development of a new natural antioxidant having no problem with safety in use and also having excellent antioxidant activity has been required.
Many studies have demonstrated the protective properties of the polyphenolic flavonoids. Antimutagenic, anticarcinogenic and immune stimulating properties of flavonoids have been reported. The flavonoids are a large group of naturally occurring polyphenols found in fruits, vegetables, grains, bark, tea and wine that have proven in vitro free-radical scavenging potential.
Anthocyanins are naturally occurring compounds that are responsible for the red, purple, and blue colors of many fruits, vegetables, cereal grains, and flowers. For example, the colors of berry fruits, such as blueberries, bilberries, strawberries, raspberries, boysenberries, marionberries, cranberries, are due to many different anthocyanins. Over 300 structurally distinct anthocyanins have been identified in nature. Because anthocyanins are naturally occurring, they have attracted much interest for use as colorants for foods and beverages. Proanthocyanins are another class of flavonoid compounds that are found in fruits and vegetables and, while being colorless, have antioxidant activities.
Recently, the interest in anthocyanin pigments has intensified because of their possible health benefits as dietary antioxidants. For example, anthocyanin pigments of bilberries (Vaccinium myrtillus) have long been used for improving visual acuity and treating circulatory disorders. There is experimental evidence that certain anthocyanins and flavonoids have anti-inflammatory properties. In addition, there are reports that orally administered anthocyanins are beneficial for treating diabetes and ulcers and may have antiviral and antimicrobial activities. The chemical basis for these desirable properties of flavonoids is believed to be related to their antioxidant capacity. Thus, the antioxidant characteristics associated with berries and other fruits and vegetables have been attributed to their anthocyanin content.
In the market today there are many products that contain antioxidants at various levels. These come in the form of foods, liquids and nutritional supplements. The richest sources of these vital nutrients commonly are found in fruits and vegetables having compounds such as Vitamin C, Vitamin E, anthocyanins, beta-carotene, and others. Antioxidants function to bind these free radicals and stabilize and scavenge them out of the system, thereby reducing the amount of damage free radicals may cause.
Since many fruits and vegetables contain these vital nutrients, it is very important to be able to assess the ability of antioxidants in these foods to absorb free radicals. USDA Researchers at Tufts University developed a laboratory test know as ORAC (Oxygen Radical Absorbance Capacity) which rates different foods according to their antioxidant content and its ability to bind these free radicals. Through this test, different foods may be compared and analyzed for their antioxidant ability.
There is a need for the identification of fruits or vegetables with high ORAC scores and the development and production of dietary supplements based thereon.